Various manual dispensers of products are well known for dispensing products such as hand and skin cleaning fluids, whether as liquids or foamed soap. Known such manual dispensers are manually operated in the sense that manual forces are applied to dispense the product. One difficulty which arises with such dispensing apparatus is to provide for timely maintenance, servicing and monitoring such as, for example, to ensure that there is always product to be dispensed and that the dispenser is operating properly.
U.S. Pat. No. 8,021,707 to Ophardt, issued Jun. 19, 2012 teaches a dispensing apparatus including a product dispenser in which product is dispensed by manual movement of an activation mechanism as, for example, by moving a lever with a person's hand, arm or foot. The dispensing apparatus includes an electrical generator for generating electrical energy as a result of the manual movement of the activation mechanism. The relative amounts of electrical energy generated are used to estimate the amount of fluid dispensed and the extent to which a fluid reservoir is full.
The present applicants have appreciated that the arrangements as taught by the above U.S. Pat. No. 8,021,707 to Ophardt, while useful to provide a rough approximation of the amount of fluid dispensed, suffer from a number of disadvantages notably that in some manners of operation of the dispenser in which fluid is dispensed, either no electrical energy is generated or the relative amounts of electrical energy generated do not provide a correlation to the amount of fluid dispensed as to be useful to estimate the fluid dispensed.
The present inventors have appreciated that the manually operated dispensers as taught by the above U.S. Pat. No. 8,021,707 suffer the disadvantage that the relative amount of electrical energy generated by the generator varies considerably under the control of the user since the user controls the force applied by the user to the lever with time in each successive power input stroke. The manual force applied in each power stroke to the lever varies as to: the force applied to the lever with time, the direction the force is applied relative to the lever and the distance over which the force is applied to the lever. This results in a wide variance of: the velocity of the lever over time during each power stroke, the acceleration of the lever with time during each power stroke and angular displacement of the lever in each power stroke. These variances give rise to a variance in the electrical power generated by the generator in each stroke and a disparity between the electrical power generated by the generator in each stroke and the fluid dispensed by the pump.
As one example, the present inventors have appreciated that some users repeatedly short stroke the manually operated lever. In an exemplary dispenser taught by the above U.S. Pat. No. 8,021,707 to Ophardt, a piston in the pump in a full stroke is moved a maximum axial distance in a piston chamber and this full stroke results from the manual movement of the lever in a power stroke through a corresponding full angular extent before the lever is permitted to return to an initial position as under the bias of a return spring. In such typical full stroke operation, a volume of fluid, for example, 2 ml is dispensed and an amount of electrical power is generated which typically has some reasonably estimable relationship to the 2 ml volume of fluid dispensed. A short stroke arises when a user moves the lever an angular extent less than the full stroke before the lever is permitted to return toward the initial position. Many users may move the lever in successive short strokes with each successive short stroke having an angular extent less than about 50% of the full angular extent, and sometimes less than about 10% of the full angular extent. The inventors have appreciated that when a user quickly applies a succession of short strokes of, for example, about 5% or less of the of the full angular extent, the dispenser will dispense the fluid however, the electrical generator will not produce any electrical power. The inventors have appreciated that the electrical generator does not produce power in a very short stroke operation arises due to the shortcomings that when the lever is first moved by a user in a power discharge stroke, the gear train linking the lever to the electrical generator has mechanical play leading to a time delay and needs some time and/or some initial minimal movement for the gear train with its disengagable one-way clutch mechanism to engage so as to drive the generator and the inertia of the generator requires some initial application of rotational force before electrical power is generated. In another manner of operation, when a user applies a succession of, for example, five such short strokes of 20% the of the full angular extent, the dispenser will typically dispense an ample volume fluid for hand cleaning, for example, about 2 ml, however, the electrical generator will typically produce significantly less electrical power, for example, less than 50% and often less than 25% of the electrical energy produced in a single full stroke. Again, this lower production of electrical power is appreciated by the inventors as arising due to the nature of the gear train and inertia of the electrical generator. The present inventors have thus appreciated that some of the arrangements of the type as taught by the above U.S. Pat. No. 8,021,707 to Ophardt suffer the disadvantages that they do not measure operation with fast successive short strokes and may not even provide any indication using the electrical generator that the pump assembly has been activated at all even though fluid may be dispensed.